diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index d0efe302b1c16f035652252a3c123cab9e56e9ed..3d31228082ea88ed8086e804430aa14d41c4583a 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -18,6 +18,7 @@
 #include <linux/capability.h>
 #include <linux/quotaops.h>
 #include <linux/types.h>
+#include <linux/writeback.h>
 #include <net/netlink.h>
 #include <net/genetlink.h>
 
@@ -52,7 +53,7 @@ void sync_quota_sb(struct super_block *sb, int type)
 {
 	int cnt;
 
-	if (!sb->s_qcop->quota_sync)
+	if (!sb->s_qcop || !sb->s_qcop->quota_sync)
 		return;
 
 	sb->s_qcop->quota_sync(sb, type);
@@ -318,9 +319,11 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 	case Q_XGETQUOTA:
 		return quota_getxquota(sb, type, id, addr);
 	case Q_XQUOTASYNC:
-		if (!sb->s_qcop->quota_sync)
-			return -ENOSYS;
-		return sb->s_qcop->quota_sync(sb, type);
+		/* caller already holds s_umount */
+		if (sb->s_flags & MS_RDONLY)
+			return -EROFS;
+		writeback_inodes_sb(sb);
+		return 0;
 	default:
 		return -EINVAL;
 	}
diff --git a/fs/xfs/linux-2.6/xfs_quotaops.c b/fs/xfs/linux-2.6/xfs_quotaops.c
index 3d4a0c84d634f947f36eb3bad04128cbc603f17d..07d67c624922ca9506e04f6d98cc37f7c3e20f1f 100644
--- a/fs/xfs/linux-2.6/xfs_quotaops.c
+++ b/fs/xfs/linux-2.6/xfs_quotaops.c
@@ -43,20 +43,6 @@ xfs_quota_type(int type)
 	}
 }
 
-STATIC int
-xfs_fs_quota_sync(
-	struct super_block	*sb,
-	int			type)
-{
-	struct xfs_mount	*mp = XFS_M(sb);
-
-	if (sb->s_flags & MS_RDONLY)
-		return -EROFS;
-	if (!XFS_IS_QUOTA_RUNNING(mp))
-		return -ENOSYS;
-	return -xfs_sync_data(mp, 0);
-}
-
 STATIC int
 xfs_fs_get_xstate(
 	struct super_block	*sb,
@@ -151,7 +137,6 @@ xfs_fs_set_xquota(
 }
 
 const struct quotactl_ops xfs_quotactl_operations = {
-	.quota_sync		= xfs_fs_quota_sync,
 	.get_xstate		= xfs_fs_get_xstate,
 	.set_xstate		= xfs_fs_set_xstate,
 	.get_xquota		= xfs_fs_get_xquota,
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index a529d86e7e73484080a32f2e9e24296aa22034ed..69d26bc0f884a225794b828fd4bfcaeb8ecf9ed1 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -22,7 +22,7 @@ static inline struct quota_info *sb_dqopt(struct super_block *sb)
 void sync_quota_sb(struct super_block *sb, int type);
 static inline void writeout_quota_sb(struct super_block *sb, int type)
 {
-	if (sb->s_qcop->quota_sync)
+	if (sb->s_qcop && sb->s_qcop->quota_sync)
 		sb->s_qcop->quota_sync(sb, type);
 }